/**

      * 找出未出现的最小正整数

      * @param A

      * @param n

      * @date 2016-10-7

      * @author shaobn

      */

     public static int findArrayMex(int[] a,int n){

         int count = n;

         int temp = 0;

         int dir = 1;

         int num = 0;

         for(int i = 0;i<count-1;i++){

             if(a[i]>a[i+1]){

                 temp = a[i];

                 a[i]= a[i+1];

                 a[i+1] = temp;

             }

             if(i==count-2){

                 count--;

                 i=-1;

             }

         }

         if(a[0]>1 || a[n-1]<1){

             return 1;

         }else {

             for(int i =0;i<n-1;i++){

                 if(a[i]>0){

                     num = i;

                     break;

                 }

             }

             if(a[num]>1){

                 return 1;

             }else if(a[num]==1) {

                 for(int i =num+1;i<n-1;i++){

                     if(a[i]-a[num]>dir){

                         return a[num]+dir;

                     }else {

                         dir++;

                     }

                 }

             }

         }

         return a[num]+dir;

     }